Chest
Laboratory and Animal InvestigationsEffects of Spontaneous Breathing During Airway Pressure Release Ventilation on Respiratory Work and Muscle Blood Flow in Experimental Lung Injury
Section snippets
Instrumentation
The principles of laboratory animal care (revised National Institutes of Health guidelines, 1985) were followed, and the study was approved by the local Laboratory Animal Care and Use Committee. Twelve pigs, mixed German country breed, weighing 10 to 19 kg (15.2 ± 0.8 kg [mean ± SEM]) were fasted for 24 h while having free access to water. Prior to instrumentation, animals were premedicated with IM ketamine (10 mg/kg), xylazine hydrochloride (2 mg/kg), and glyopyrronium bromide (15 μg/kg) and
Results
For validation of the microspheres technique, adequate mixing of injected microspheres and even distribution of blood flow to the various organs were indicated by highly significant correlations between the number of microspheres trapped in the two reference blood samples (5,030 ± 619 microspheres per sample vs 4,848 ± 556 microspheres per sample, r = 0.95) and the blood flows to the right and left adrenal glands (1.99 ± 0.22 mL/g/min vs 1.91 ± 0.25 mL/g/min, r = 0.94) [p < 0.0001,
Discussion
The aim of our study was to investigate the effects of spontaneous breathing on respiratory work and RMBF in a pig model with oleic acid-induced lung injury. We found that PTPinsp and diaphragmatic blood flow markedly increased when animals with lung injury were breathing spontaneously at ambient Paw, and that ventilatory support with APRV resulted in a reduction of PTPinsp and diaphragmatic blood flow to normal physiologic values not different from those obtained in animals with normal lungs
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